The present invention relates to a mounting assembly for a motor-vehicle seat. More particularly this invention concerns such an assembly which allows the seat to be locked in any of a plurality of positions spaced apart in the direction of travel of the vehicle.
At least the driver's seat of a motor vehicle is normally mounted in such a manner that it can be secured in any of a plurality of positions spaced along the direction of travel of the vehicle. This adjustment allows the seat to be moved closer to the steering wheel and pedals for a short driver and farther away for a tall driver.
To this end the seat is normally carried on a pair of slides each movable along a respective floor-mounted guide rail. An adjustment member carried on each slide is displaceable into and out of engagement with any of a plurality of position-defining recesses on the respective floor-mounted guide. A handle can lift these adjustment members out of the recesses in which they are engaged to allow the person sitting on the seat to move it forwardly or backwardly. Thereafter the handle is released to allow engagement of the adjustment members into the nearest recesses.
It is essential in such arrangements, however, that the mounting assembly be capable of holding the seat and preventing it from sliding even when considerable forces are exerted between the seat and the support. Thus, for instance, it is necessary that the seat not slip if the vehicle is sharply accelerated or decelerated.
One arrangement is known wherein each of the supports is provided with a detent formed as a row of sawteeth. The relatively sharply inclined flanks of the one detent are in front of the relatively flatly inclined flanks of the same detent on one side and in the opposite side this arrangement is reversed. The adjustment members are each engageable in the respective row of teeth. In addition a so-called safety member is provided which extends above these teeth and which normally is held by a relatively weak leaf spring out of engagement from these teeth. This safety member can, however, be displaced into engagement with the teeth in such a manner as rigidly to lock the slide and support together, even in a relatively violent collision.
In this arrangement the safety members are so weighted and dimensioned that whenever a horizontal force above a predetermined relatively low limit is effective on them, as for instance during rapid acceleration or deceleration, they inertially swing into engagement with the respective detents and lock the seat. Thus the necessary function of preventing the seat from sliding during a rapid acceleration or deceleration is attained.
Such an arrangement has, however, the considerable difficulty that it is necessary to dimension the leaf spring that holds the safety members in their unengageable positions very exactly. If the spring is too strong the safety mechanism will not respond; if too weak the seat will be locked and adjustment will be impossible at any time. Similarly once such an arrangement is actuated it frequently becomes very difficult to unlock the seat. A final difficulty with this arrangement is that it is relatively complex and expensive to manufacture, while at the same time only allowing the seat to be locked in any of a plurality of predetermined positions.